Fig. 2
From: Receptor-binding loops in alphacoronavirus adaptation and evolution
HCoV-229E RBD in complex with the ectodomain of hAPN. a The complex between dimeric hAPN (domain I: blue, domain II: green, domain III: brown, and domain IV: yellow) and the HCoV-229E RBD (purple) is depicted in its likely orientation relative to the plasma membrane. The hAPN peptide and zinc ion (red spheres) binding sites are located inside a cavity distant from the virus binding site. Black bars represent the hAPN N-terminal transmembrane region. b Ribbon representation of the HCoV-229E RBD (gray) in complex with hAPN (same coloring as in a). The three receptor-binding loops are colored, orange (loop 1), cyan (loop 2), and purple (loop 3). N and C label the N- and C-termini of the RBD. c Atomic details of the interaction at the binding interface. Hydrogen bonds and salt bridges are indicated by dashed lines. Red and blue correspond to oxygen and nitrogen atoms, respectively. Loop and hAPN coloring as in b
